An amalgam is a mixture of a liquid metal, such as mercury or gallium, and one or more powdered metals, such as nickel, copper, silver, gold, antimony, tin, cobalt, magnesium, antimony, manganese, chromium, titanium, molybdenum, aluminum, iron, etc. Amalgams can be formed at or near room temperature but when cured and hardened, have melting temperatures well above room temperature. It has been suggested that amalgams be used as a bonding material for bonding together the parts of a solid state device. For example, for bonding the cover plate to a housing of a solid state device package as described in the copending application of E. Carnall Jr. et al (Ser. No. 07/594,879) filed concurrently herewith and entitled "Hermetically Sealed Microelectronic Package and Method of Making the Same", or for bonding a solid state device to a terminal board as described in the copending application of D. Bull et al. (Ser. No. 07/594,786), filed concurrently herewith and entitled "Bonding of Solid State Device to Terminal Board". The use of an amalgam as a bonding material in solid state devices is particularly useful where the device cannot withstand the high temperature required for most solders which are generally used, but where the bonding material must hold the bond at the elevated temperatures at which the solid state device may operate. In order to facilitate the use of an amalgam as a bonding material, it would be desirable to have the amalgam in the form of a solid preform of a shape and size to correspond with the parts to be bonded together. Therefore, it would be desirable to be able to form an amalgam into a solid sheet from which the preforms could be formed. However, the solid sheet must be able to be stored for periods of time after being formed until it is required for use.